1. Field of the Invention
This invention relates to a lens interchange type single-lens reflex camera system and an intermediate barrel mountable between a camera body and an interchangeable lens.
2. Related Background Art
When an intermediate barrel like a rear focus converter is mounted between an interchangeable lens and a camera body, the information of the interchangeable lens to be transmitted to the camera body, for example, the focal length and the open F-value become the combined value of the information of the interchangeable lens and the rear focus converter. As a system for transmitting the obtained combined value to the camera body, there is U.S. Pat. No. 4,548,488. This system is such that it receives the information from the interchangeable lens and calculates the information by the rear focus converter, thereby transmitting the obtained combined value to the camera body.
The lens information regarding the auto-focus, for example, the spherical aberration of a lens, is important information for determining the accurate position of the point of focus. As regards this spherical aberration, although the spherical aberration of each of the interchangeable lens and the rear focus converter is known, the combined spherical aberration of the two cannot be determined by a simple calculation. Thus, in the above-described prior art, the combined open F-value, the focal length, etc. can be transmitted to the camera body, but the information of the combined aberration, etc. cannot be accurately transmitted to the camera body.